MONTPELIER — The state Public Service Board has ordered Vermont Gas Systems to stop digging for its pipeline near power lines owned by the Vermont Electric Cooperative because of nearby pesticide concerns.Vermont Public Radio reports the state Agency of Natural Resources alerted the company to the possibility that soil contaminated with Pentachlorophenol, or PCP, could be disturbed by pipeline construction. The cooperative’s poles have been treated with PCP, also used as a wood preservative. The EPA has found it to be toxic.Last week, Vermont Gas said in a letter to the board “it would be prudent” for the company to develop a soil management plan for the project. In response, the board required the company to stop digging until a plan has been reviewed and approved by the board.